This invention relates to valves for controlling flows of fluids. More particularly the invention relates to valves for use in systems in which a valve member is controlled to turn on or off a main fluid flow by fluid at a control port. The invention also relates to a control valve, or xe2x80x9cpilotxe2x80x9d valve, for use in controlling another valve. The invention has particular application in controlling the supply of water to faucets. Preferred embodiments of the invention provide xe2x80x9chands freexe2x80x9d control of faucets.
Pubben, U.S. Pat. No. 5,505,227, discloses a xe2x80x9chands freexe2x80x9d system for controlling the flow of water to a faucet. The system includes a pilot valve which provides pilot water of controlled pressure to operate diaphragm valves in a control block. The valves in the control block may be respectively connected between hot and cold water supply lines and a faucet. The pilot valve may be located in a position where it can be operated by a user""s knee, elbow or foot.
Key advantages of a system of this general type are that a user does not need to touch any valve by hand. Therefore such valves can be operated hygienically. For this reason, hands free valve systems have become widely used by health professionals such as dentists and doctors. Such systems also have the advantage that no electrical power or compressed air is needed for operation.
Although the Pubben system is very effective and has had significant commercial success there are some areas where it could usefully be improved. In particular, it has been observed that flow resonances may occur when the Pubben valve opens or closes. This can cause the system to make undesirable noises. Such resonances may continue for one second, or more, in some cases. The resonances can be exacerbated if the pilot valve has an intermediate position in which its output is simultaneously connected to both lower and higher pressure fluid supplies.
Further, the valve tends to close rather suddenly which precipitates water hammer. Water hammer is caused by the sudden stopping of a moving water column and results in high amplitude pressure waves which can bounce back and forth in plumbing pipes causing unpleasant noises and accelerating wear of the valve. After several years of use the wear caused by water hammer and valve resonances can cause the diaphragms in the valve block to become perforated, especially in their areas around the valve exit ports. Finally, the 3-way sliding spindle valves which are commonly used as pilot valves have seals which can wear undesirably rapidly.
Austin Jr. et al., U.S. Pat. No. 5,203,373 discloses another hands free faucet system. The Austin et al. system also uses pilot valves to control the flow of water through a pair of main valves. Austin Jr. et al. does not appear to provide any mechanism for reducing or eliminating water hammer and resonance effects. The inventors therefore are of the view that the Austin Jr. et al. valve system suffers from the same defects identified above.
This invention provides a fluid control valve having novel features which may be used in a system for controlling the flow of fluids. The fluid control valve may be used, for example, to control the flow of water from a water faucet. The fluid control valve can be controlled by a pilot valve. The invention also provides a pilot valve which may be used either with the fluid control valve of the invention or in other settings.
Accordingly, one aspect of the invention provides a fluid control valve comprising: a body having an inlet, an outlet and a fluid path extending between the inlet and the outlet; a chamber in the body the chamber in fluid communication with a control port; a valve member movably disposed within the body for free motion toward or away from a valve seat along a trajectory, the valve member having a closed position wherein the valve member is sealed against the valve seat and the fluid path is blocked by the valve member and an open position wherein the fluid path is not blocked by the valve member, the valve member movable toward the closed position along the trajectory by increasing a fluid pressure within the chamber. When the valve member is in an intermediate position between its open and closed positions, the fluid path extends through a constriction zone between the body and a surface on the valve member which is oriented substantially parallel to the trajectory. The fluid path also extends through a stagnation zone between the body and a surface on the valve member which extends transversely to the trajectory. The fluid velocity in the stagnation zone is less than the fluid velocity in the constriction zone. Consequently, the fluid pressure is greater in the stagnation zone than it is in the constriction zone. The increased fluid pressure tends to slow closure of the valve.
In preferred embodiments the constriction zone is annular. Preferably the valve comprises a diaphragm and the valve member is on the diaphragm.
The valve may include a plug portion on the valve member. The plug portion is received in an aperture in a valve seat. In preferred embodiments an end portion of the plug has a conical configuration. Most preferably the end portion of the plug has a cone angle in the range of 30 to 60 degrees.
Some embodiments of the invention include filter in the fluid path. The filter may be an annular filter located in an annular chamber surrounding the valve seat structure.
Some embodiments of the invention include a flow restriction chamber. The flow restriction chamber provides resistance to the flow of fluid but can have internal dimensions larger than an orifice sized to provide the same resistance. Consequently the flow restriction chamber is less susceptible to becoming obstructed by solid particles or deposits than would be a simple orifice. The flow restriction chamber comprises a substantially tangential inlet in a peripheral portion of the chamber and an outlet in a central portion of the flow restriction chamber. The flow restriction chamber inlet is in fluid communication with the valve inlet. The outlet capable of being placed in fluid communication with the chamber in the body of the valve. In preferred embodiments, the flow restriction chamber is substantially conical, the flow restriction chamber inlet is near a base portion of the flow restriction chamber and the flow restriction chamber outlet is in an apex portion of the flow restriction chamber. Most preferably the flow restriction chamber comprises a conical insert portion extending axially into the flow restriction chamber from the base portion.
Another aspect of the invention combines the valve with a 3-way pilot valve, the pilot valve having an inlet port communicating with the fluid control valve inlet through a pilot fluid path, an outlet port in fluid communication with the fluid control valve outlet, and a pilot port in fluid communication with the control port of the fluid control valve, the pilot valve having a first configuration wherein its inlet and pilot ports are in fluid communication and a second configuration wherein its outlet and pilot ports are in fluid communication.
In preferred embodiments the valve comprises a filter located in the fluid path and in the pilot fluid path. The fluid path passes through larger passages extending in a first direction in the filter and the pilot fluid path passes through smaller passages extending in a second direction through the filter. Most preferably the filter comprises an annular filter located in an annular chamber in the valve body, the first direction is a substantially axial direction and the second direction is a substantially radial direction.
The pilot valve may comprise a body (which may be part of the valve body or a separate body), a first valve member movably disposed within the body, the first valve member having an open position wherein the inlet and pilot ports are in fluid communication and a closed position wherein the inlet and pilot ports are not in fluid communication, the first valve member arranged so that it is held in its closed position when a fluid pressure at the inlet port is higher than a fluid pressure at the pilot port; a second valve member movably disposed within the body, the second valve member having an open position wherein the outlet and pilot ports are in fluid communication and a closed position wherein the outlet and pilot ports are not in fluid communication the second valve member arranged so that it is held in its closed position when a fluid pressure at the pilot port is higher than a fluid pressure at the outlet port; a rocker arm in the body; a spring biassing the rocker arm against the first and second valve members, the spring holding the rocker arm in a position wherein the first valve member is in its open position and the second valve member is in its closed position; and, an operating member for displacing the rocker arm into a position wherein the first valve member is in its closed position and the second valve member is in its open position. The pilot valve may be used on its own, in combination with a valve according to the invention or in combination with other valves or fluidic devices.
Another aspect of the invention provides a valve, generally as described above, in combination with a two-way pilot valve connecting the chamber and the outlet. The pilot valve has an open state wherein the chamber is in fluid communication with the outlet through the pilot valve and a closed state wherein fluid cannot freely flow from the chamber to the outlet. The valve comprises a pilot fluid passage communicating between the chamber and the inlet. The pilot fluid passage providing significantly more restriction to fluid flow than does the pilot valve in its open state.
Still another aspect of the invention provides a valve comprising: a valve body having an inlet, an outlet, a valve seat structure between the inlet and the outlet and fluid path extending between the inlet and the outlet through an aperture in the valve seat structure, the valve seat structure comprising generally cylindrical inner and outer walls and an annular valve seating surface; a diaphragm comprising a movable valve member portion, the valve member portion located between the valve seat structure and a cavity in the housing, the valve member portion comprising an annular groove capable of receiving the valve seating surface; and, a fluid passage in the body through which fluid may be introduced to the chamber to vary a fluid pressure within the cavity. The valve member portion has a closed position wherein fluid flow along the fluid path is blocked by the valve member portion, an open position wherein fluid can flow along the fluid path from the input to the output, and an intermediate position between the open and closed positions. In the intermediate position a first constriction zone in the fluid path is defined between the inner wall of the valve seat structure and an inner wall of the groove, a second constriction zone in the fluid path is defined between the outer wall of the valve seat structure and an outer wall of the groove, and a stagnation zone is defined in the groove adjacent the valve seating surface. A cross sectional area of the fluid path is significantly greater in the stagnation zone than in either of the first and second constriction zones.
Yet another aspect of the invention provides a method for operating a 3-way pilot valve. The method comprises: providing a pilot valve having 1) a valve body; 2) a first valve member movably disposed within the body, the first valve member having an open position wherein the inlet and pilot ports are in fluid communication and a closed position wherein the inlet and pilot ports are not in fluid communication, the first valve member arranged so that it is held in its closed position when a fluid pressure at the inlet port is higher than a fluid pressure at the pilot port; 3) a second valve member movably disposed within the body, the second valve member having an open position wherein the outlet and pilot ports are in fluid communication and a closed position wherein the outlet and pilot ports are not in fluid communication the second valve member arranged so that it is held in its closed position when a fluid pressure at the pilot port is higher than a fluid pressure at the outlet port; and, 4) a rocker arm engaged with the first and second valve members. The method further includes: applying fluid at a higher pressure to the inlet port and applying fluid at a lower pressure to the outlet port; biassing the rocker arm against the first and second valve members to hold the first valve member in its open position and the second valve member in its closed position; displacing the rocker arm to allow the first valve member to move to its closed position while a pressure differential across the second valve member prevents the second valve member from moving to its open position; and, continuing to displace the rocker arm after the first valve member has reached its closed position until the second valve member is displaced to its open position.
Further features and advantages of the invention are described in the following description which highlights specific embodiments of the invention.